[PATCH 1/5] tcp/md5: Don't BUG_ON() failed kmemdup()
From: Dmitry Safonov <hidden>
Date: 2021-11-05 01:50:02
Also in:
linux-crypto, lkml
Subsystem:
networking [general], networking [tcp], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Neal Cardwell, Linus Torvalds
static_branch_unlikely(&tcp_md5_needed) is enabled by
tcp_alloc_md5sig_pool(), so as long as the code doesn't change
tcp_md5sig_pool has been already populated if this code is being
executed.
In case tcptw->tw_md5_key allocaion failed - no reason to crash kernel:
tcp_{v4,v6}_send_ack() will send unsigned segment, the connection won't be
established, which is bad enough, but in OOM situation totally
acceptable and better than kernel crash.
Introduce tcp_md5sig_pool_ready() helper.
tcp_alloc_md5sig_pool() usage is intentionally avoided here as it's
fast-path here and it's check for sanity rather than point of actual
pool allocation. That will allow to have generic slow-path allocator
for tcp crypto pool.
Signed-off-by: Dmitry Safonov <redacted>
---
include/net/tcp.h | 1 +
net/ipv4/tcp.c | 5 +++++
net/ipv4/tcp_minisocks.c | 5 +++--
3 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/include/net/tcp.h b/include/net/tcp.h
index 4da22b41bde6..3e5423a10a74 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h@@ -1672,6 +1672,7 @@ tcp_md5_do_lookup(const struct sock *sk, int l3index, #endif bool tcp_alloc_md5sig_pool(void); +bool tcp_md5sig_pool_ready(void); struct tcp_md5sig_pool *tcp_get_md5sig_pool(void); static inline void tcp_put_md5sig_pool(void)
diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
index b7796b4cf0a0..c0856a6af9f5 100644
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c@@ -4314,6 +4314,11 @@ bool tcp_alloc_md5sig_pool(void) } EXPORT_SYMBOL(tcp_alloc_md5sig_pool); +bool tcp_md5sig_pool_ready(void) +{ + return tcp_md5sig_pool_populated; +} +EXPORT_SYMBOL(tcp_md5sig_pool_ready); /** * tcp_get_md5sig_pool - get md5sig_pool for this user
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index cf913a66df17..c99cdb529902 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c@@ -293,11 +293,12 @@ void tcp_time_wait(struct sock *sk, int state, int timeo) tcptw->tw_md5_key = NULL; if (static_branch_unlikely(&tcp_md5_needed)) { struct tcp_md5sig_key *key; + bool err = WARN_ON(!tcp_md5sig_pool_ready()); key = tp->af_specific->md5_lookup(sk, sk); - if (key) { + if (key && !err) { tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); - BUG_ON(tcptw->tw_md5_key && !tcp_alloc_md5sig_pool()); + WARN_ON_ONCE(tcptw->tw_md5_key == NULL); } } } while (0);
--
2.33.1